Liquid Chromatography Detectors - The Electrical Conductivity Detector > Page 86

 

Figure 55.  The Electrical Conductivity Detector

 

The center sensors are made from short lengths of stainless steel tubing (about 0.020 in I.D. and 1/16 in O.D). The two tubes slide into a PTFE tube and the space (inside the PTFE tube) between the two tubes is sensing volume. The lower sensor is very similar, but two lengths of stainless steel tube are employed, both of which are isolated from any other metal connection by PTFE tubing. The two electrodes are, thus, electrically isolated (this can be advanatgeous for certain types of electronic measuring circuits). These sensors have sensing volumes of only a few nanoliters and are, thus, often used in detectors for capillary electrophoresis.